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Results for “Retrocochlear Diseases”

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PubMed1995

Neurologic features of chronic minamata disease (organic mercury poisoning) and incidence of complications with aging.

To elucidate the neurologic features of chronic Minamata disease, and the incidence of complications with aging, we studied 80 patients with documented Minamata disease (organic mercury poisoning) from 1986 to 1994 (mean age: 63 years). Of the cardinal neurologic findings, sensory impairment was seen with highest frequency in 98.8% of patients limited to the extremities in 86.3%. Impairment of lower extremity coordination was observed in 60%, constriction of the visual field in 51.9%, and retrocochlear hearing loss in 41%. To assess age-related complications, patients were separated into three groups by age: Group I (10 to 39 years); Group II (40 to 69 years); Group III (> or = 70 years). The incidences of hypertension and cerebrovascular diseases, organic ophthalmologic disorders (including cataracts), presbyacusis, and cervical spondylosis deformans increased significantly with age. Compared with a preceding survey (1981 to 1985, 171 patients, mean age: 63.5 years), the incidences of complicated hypertension and cataracts had decreased, whereas those of cerebrovascular disease and retinitis pigmentosa remained unchanged. The incidences of abnormal brain computed tomography (CT), presbyacusis, cervical spondylosis deformans, and positive tests for urine sugar also increased. The incidences of these complications other than retinitis pigmentosa were similar to those in the general population. These results accurately reflect the recent epidemiological disease tendencies in Japan toward a decreased incidence of hypertension and an increased incidence of diabetes.

Adolescent↗

PubMedDate not supplied

Contrast enhancement of the labyrinth on MR scans in patients with sudden hearing loss and vertigo: evidence of labyrinthine disease.

The sudden onset of hearing loss and vertigo presents a difficult diagnostic problem. We describe the finding of labyrinthine enhancement on MR images in five patients with sudden unilateral hearing loss or vertigo or both and correlate the MR findings with audiologic and electronystagmographic studies. All patients were studied with T2-weighted axial images through the whole brain, contrast-enhanced 3-mm axial T1-weighted images through the temporal bone, and enhanced T1-weighted sagittal images through the whole brain. Cochlear enhancement, on the side of hearing loss only, was found in all five patients. The presence of associated vestibular enhancement correlates with objective measures of vestibular function on the electronystagmogram. In two patients, the resolution of symptoms 4-6 months later correlated with resolution of the enhancement on gadopentetate dimeglumine-enhanced MR images. Two patients had luetic labyrinthitis. No labyrinthine enhancement was seen in a series of 30 control subjects studied with gadopentetate dimeglumine-enhanced MR using the same protocol. Labyrinthine enhancement in patients with auditory and vestibular symptoms is a new finding and is indicative of labyrinthine disease. While abnormalities on electronystagmograms and audiograms are nonspecific and indicate only a sensorineural problem, gadopentetate dimeglumine-enhanced MR may separate patients with retrocochlear lesions, such as acoustic neuromas, from those in whom the abnormal process is in the labyrinth or is intraaxial. This group of patients underscores the importance of identifying and commenting on the structures of the membranous labyrinth when evaluating MR studies of the internal auditory canal and the cerebellopontine angle in individuals with hearing loss.

Adult↗

PubMed1988

Histologic findings in two very small intracanalicular solitary schwannomas of the eighth nerve: II. "Onion bulbs".

An "onion bulb" is a descriptive histologic term referring to concentric layers of Schwann cell processes about a myelinated nerve fiber. Between the layers of Schwann cells are increased amounts of longitudinally oriented collagen fibers. It is thought that onion bulbs form as a result of sequential segmental demyelination and remyelination attempts. This process can become so severe that the myelinated fiber loses its myelin and ultimately degenerates; however, many fibers remain viable and thinly myelinated. The physiologic effect of "onion bulbs" is to markedly decrease conduction velocity in the fiber affected. In the auditory system, incompletely myelinated cochlear nerve fibers in the infant and in patients with multiple sclerosis show delays of the auditory evoked potential latencies and psychoacoustic retrocochlear patterns. No anatomic substrate has been identified for these auditory tests patterns in the acoustic tumor (solitary schwannoma of the eighth nerve). Two very small intracanalicular acoustic tumors were resected en bloc with the nerve of origin, serially sectioned, stained for neural tissue, and studied by light microscopy. In both tumors, histologic findings consistent with onion bulb formation were discovered about some of the myelinated nerve fibers found deeply incorporated in the tumor mass. These findings suggest that demyelination, perhaps with the formation of onion bulbs, may be a histopathologic correlate for retrocochlear dysfunction seen in acoustic tumors.

Cranial Nerve Neoplasms↗

PubMedDate not supplied

Value of special auditory tests in the latero-medial inferior pontine syndrome.

Results from a special battery of auditory tests are used to document, for the first time, recovery from a total unilateral hearing loss occurring as part of a latero-medial inferior pontine syndrome. Although sensitivity for pure tones and speech was regained within two months of onset, definite retrocochlear signs persisted for nine months. The tests which best demonstrated the lingering retrocochlear abnormality were binaural masking level difference procedures for 500 Hz pure tones and speech and examination of the amplitude of the acoustic reflex over a ten second time period. The relative sensitivity of other speech and pure tone tasks in detecting the retrocochlear problem is detailed.

Animals↗

PubMed2003

[Progressive bilateral hearing loss with superficial hemosiderosis of the central nervous system: contribution of cochlear implantation].

Two cases of progressive bilateral hearing loss associated with superficial hemosiderosis of the central nervous system are reported. This is a rare disease caused by repetitive hemorrhage in subarachnoid spaces with hemosiderin deposits on the brain surface and cranial nerves. MRI provided the etiologic diagnosis in both cases based on typical low-density signals from the brain, the brainstem, and the cerebellar surfaces on T1 and T2 sequences. In one case a fourth ventricle ependymoma, which was the probable cause of hemosiderosis, was also discovered. Based on a literature review, we discuss the pathophysiological hypotheses, the modalities for treating hearing loss including cochlear implantation despite retrocochlear sensorineural hearing loss.

Adult↗

PubMed1996

Osteoma of the internal auditory canal.

We present a case of an osteoma of the internal auditory canal, which was surgically removed with symptomatic improvement. We describe CT, MRI, histological and operative findings, with a review of the proposed aetiology. The implications for imaging in the investigation of retrocochlear lesions are discussed.

Adult↗

PubMed1981

Phase reversal in brain stem responses: its use in the detection of asymmetry in the auditory pathways.

Electrode placement is an important consideration in the recording of a large-amplitude stable response. In this study, brain stem auditory-evoked potentials (BAEP) were obtained from subjects and patients under two electrode configurations, namely 'vertex-mastoid' and 'mastoid-mastoid'. The BAEP waveforms to ipsilateral, contralateral and binaural stimulation were examined for their phase relation with respect to stimulation. In the mastoid-mastoid recording mode, a complete polarity reversal was shown upon changing stimulation from the ipsilateral (with respect to the active input) to the contralateral ear. On simultaneous binaural stimulation, the response was shown to summate to zero. This observation has led to the objective assessment of asymmetry of hearing. Several patients exhibiting recruitment were tested under the mastoid-mastoid recording configuration with binaural stimulation. The results show that a summated 'null' response only occurs at an intensity level where loudness equality is attained at the two ears and recruitment is complete. Applied in this way the technique has promising application in the determination of the presence or absence of recruitment and hence in the differential diagnosis of cochlear and retrocochlear lesions.

Auditory Pathways↗

PubMed1985

Patterns of phoneme identification error in cochlear and eighth-nerve disorders.

The purpose of this study was to determine whether patterns of phoneme identification error differ among listeners with cochlear and retrocochlear auditory disorder. Speech intelligibility performance was analyzed in 15 patients with confirmed eighth-nerve disorder and in 15 patients with cochlear disorders, matched to the retrocochlear group for age and audiometric configuration, using confusion matrices derived from responses to a monosyllabic word list. Results indicated that: (1) vowel errors were more prevalent in the retrocochlear group and varied directly with increasing stimulus presentation level; and (2) consonant errors did not differ in type or relative frequency between the two groups, nor was there a level-dependent effect for consonant errors. These results are supported by the results of closed-set vowel identification tests and thus do not appear to be an artifact of open-set testing. Vowel errors may account for a major part of the speech 'rollover' phenomenon typical of retrocochlear auditory dysfunction.

Adult↗

PubMed1981

Automatic analysis of electro-oculographic (EOG) recordings. Application to audio-vestibular diagnosis.

An automatic, computerized system for analysis of the ocular movements in nystagmus, slow pursuit and saccades is presented. The performance of the system has been tested in healthy subjects, as well as in patients with peripheral or brainstem audio-vestibular disorders. The automatized procedure enables an extended application of opto-motor tests in the clinical examination of patients with suspected retrocochlear and brainstem involvement.

Computers↗

PubMed1989

Immunology of hearing: experiments of nature.

Cellular and humoral immune reactions may play a role in the ethiopathogenesis of an audiovestibular dysfunction. Immune-mediated inner ear disorders can be of cochlear and retrocochlear origin. Autoimmunity plays occasionally a role, but is certainly not obligatory.

Antibody Formation↗

PubMedDate not supplied

Sudden hearing loss and autoimmune inner ear disease.

This case report describes the audiologic and medical diagnostic evaluations, results, and treatment options in a patient with a classic presentation of immune-mediated sensorineural hearing loss, commonly called autoimmune inner ear disease (AIED). It reviews findings of the basic battery, immittance audiometry, transient otoacoustic emissions, and auditory brainstem response measures and medical findings over more than 2 years. AIED generally causes asymmetric bilateral sensorineural hearing loss with atypical configuration. Although hearing loss is generally fluctuant, the overall pattern is usually rapid progression, particularly in the absence of early medical intervention. Word recognition is usually disproportionately poor. In our case, otoacoustic emissions and auditory brainstem responses suggest both cochlear and retrocochlear involvement and may initially appear to be inconsistent with pure-tone thresholds. Audiologists must be familiar with AIED because early identification is critical. Additionally, an immunologic basis may be a factor in other disorders, including many cases of Meniere's disease.

Adult↗

PubMed1983

Reflex "delay" in sensorineural hearing-loss.

Delay of the acoustic reflex is concerning the latency and the rise-time of the response. The magnitude of these parameters is correlated with the stimulus characteristics but it is also modified by the instrumentation. Normative data obtained with commercial instruments demonstrate statistically meaningful differences of latency depending on age groups, ipsi-or contralateral recording, monophasic or biphasic deflection, which is also a normal response in about 12% of ears. The value are comprised within 150 ms for ipsilateral recording and 200 ms for the contralateral recording. The interaural latency difference (ILD) is not exceeding 40 ms. In cochlear deafness (50 cases with Ménière's disease and 50 cases with acoustic or ototoxic lesions) the latency values are slightly shorter than normal in 25% of the cases. This is better demonstrated when ILD can be evaluated with the normal ear. Also rise-time is similarly reduced. In retrocochlear lesions, when a cochlear involvement is not superimposed latency and rise-time are lengthened. Also in these cases ILD values are very important. It must be recalled that an acoustic reflex delay has been observed also in cases of brain-stem involvement.

Hearing Loss, Sensorineural↗

PubMed1993

Tinnitus suppression by electrical promontory stimulation in sensorineural deaf patients.

In 62 patients, whose hearing acuity was normal or profoundly impaired, tinnitus suppression was attempted through electrical promontory stimulation (EPS) with a Promontory Stimulator (Cochlear Co.). The causes of tinnitus were idiopathic sudden deafness, ototoxicity, noise induced hearing loss, labyrinthitis, Meniere's disease, acoustic neuroma and unknown origin. Reduction of tinnitus was achieved in 46 of 68 ears (67.6%). Of these, EPS was most effective in cases of noise induced hearing loss (100.0%; 3/3), followed by those of idiopathic sudden deafness (87.5%; 14/16), Meniere's disease (83.3%; 5/6), labyrinthitis (75.0%; 6/8), ototoxicity (66.6%; 4/6) and unknown origin (76.4%; 13/17). The treatment had hardly any effect on patients with acoustic neuroma (8.3%; 1/12). Twenty patients reported residual inhibition with a duration ranging from several hours to one week. Our results suggest that tinnitus due to cochlear lesions can be suppressed by EPS. This technique may also be useful for differentiation between tinnitus resulting from cochlear lesions and from retrocochlear lesions.

Adolescent↗

PubMedDate not supplied

Ct air-contrast scanning of the internal auditory canal.

Two hundred and four patients with audiometric and vestibular findings suggestive of a retrocochlear lesion were studied prospectively by computed tomographic scan with air contrast of the internal auditory canal. With this technique tumor limits are clearly defined. In the absence of disease the internal auditory canal has been completely air-filled in over 97% of cases. Soft tissue masses occluding the internal auditory canal were demonstrated in 11 patients. Four studies were inconclusive and there was one false positive. Headaches have been the only side effect and there have been no complications. In reporting their results the authors examined the indications, accuracy and limitations of this technique. This study demonstrates that computed tomographic scan with air contrast of the internal auditory canal should be considered as the radiologic procedure of choice for the evaluation of small acoustic tumors.

Cerebellar Neoplasms↗

PubMed1984

Quantitative analysis of the visual vestibulo-ocular reflex using sinusoidal rotation in patients with peripheral vestibular disorders.

In order to investigate interaction of the vestibular and optokinetic systems in patients with peripheral vestibular disorders, the visual vestibulo-ocular reflex (V-VOR) gain in 49 patients with peripheral vestibular disorders was quantitatively measured by using pendular harmonic sinusoidal rotation with optokinetic stationary stimuli. The patients were rotated sinusoidally both with eyes closed and open at an amplitude of 240 degrees and at a frequency of 0.1 Hz (peak velocity 75.4%s). Comparing the vestibulo-ocular reflex (VOR) and V-VOR gains in the patients with definite Meniere's disease (23 cases), benign paroxysmal positional vertigo (BPPV, 13 cases) and sudden deafness with vertigo or dizziness (13 cases), the VOR-DP and normal V-VOR gain were more frequently observed in patients with Meniere's disease (13 cases) and sudden deafness (7 cases) than in those with the BPPV (3 cases). In the four patients with bilateral Meniere's disease and sudden deafness, abnormally decreased VOR-gain (under 0.55) in the bilateral directions with slightly decreased V-VOR gain was measured when tested independently. However, abnormal V-VOR gain was observed in only one case of sudden deafness due to retrocochlear lesions. From our VOR and V-VOR gain observations comparing the caloric responses, we have concluded that the comparison of VOR with V-VOR gains provides additional information for evaluation of peripheral vestibular disorders as well as central nervous system disorders.

Computers↗

PubMed1995

High-resolution MRI of the human cochlea.

The majority of magnetic resonance imaging (MRI) studies in neurotology concern the evaluation of retrocochlear pathologies or temporal bone lesions. Recently, quite a number of investigators have attempted to use imaging diagnosis to obtain a diagnosis and manifest the pathological findings of Meniere's disease. However, there is no evidence that endolymphatic hydrops in patients with Meniere's disease can be identified by imaging techniques. In this study we could depict Reissner's membrane clearer than before with the use of image processing. At the present time, we cannot apply the 2.11T MRI machine to patients under FDA regulation. We believe that MRI diagnoses of endolymphatic hydrops and small lesions of the internal structures of the inner ear will be possible in the near future.

Adult↗

PubMed1981

Sound localization. Part II: a clinical procedure.

Difficulty in localizing sound has been shown to be associated with severe unilateral hearing impairment, middle-ear conditions and lesions of the cerebello-pontine angle. This was in contrast to the performance of subjects with cochlear lesions and certain brain conditions who had mainly normal ability to localize sound. The investigation appeared to indicate that a sound localization test in the horizontal plane using low frequency stimuli may be a useful addition to the test battery employed in the differential diagnosis of cochlear and retrocochlear lesions involving the cerebello-pontine angle.

Adolescent↗

PubMed2000

[Differential diagnosis of unilateral hearing loss].

There are two main kinds of hearing disorders: sensorineural and conductive. Sensorineural hearing loss is a common disorder that results from damage to the inner ear in over 95% of all cases; therefore, retrocochlear hearing disorders are rare and cannot be differentiated from sensory losses by clinical symptoms alone. Unilateral hearing loss entails many problems in hearing during the entire life of the affected patients. Conductive deafness has a readily determined etiology in most cases. In contrast, unilateral sensorineural hearing loss requires more refined and extensive investigation. The etiology of an asymmetric sensorineural hearing loss can often be difficult to determine. Because a wide variety of pathologic processes may be responsible for the hearing loss, numerous diagnostic tests are usually used during initial evaluation, including pure-tone audiometry, acoustic reflex testing, imaging, serologic testing, and auditory brainstem response testing. The most frequent causes of unilateral sensorineural hearing loss were sudden deafness, Menière's disease and cerebellopontine angle tumors. Early diagnosis of acoustic neuroma or other lesions of the internal auditory meatus or cerebello-pontine angle requires special attention. The patient with an acoustic neuroma may present to the otologist with a variety of clinical features. Classically these include a retrocochlear pattern of sensorineural hearing loss, reduced vestibular response on caloric testing and a pathological auditory brainstem response. Magnetic resonance imaging offers greater specificity than computed tomography. Therapy of unilateral sensorineural hearing loss includes efforts to treat known causes either medically or surgically.

Diagnosis, Differential↗